Mitt Romney faces a crucial test Thursday, when he must lay out his immigration policy in order to deny President Obama a potent campaign weapon.

Romney’s momentum has stalled since Obama announced his administration would halt deportations of illegal immigrants brought to the United States as children, a move Republicans acknowledged as deft since it energized the Hispanic voters the president is desperate to get to the polls. 

{mosads}It also divided Republicans, putting pressure on Romney to unite his party by giving a forceful presentation of his views on immigration that would offer hope to Hispanics without angering the party’s conservative base.

Romney officials huddled with advisers Wednesday to craft their message for Thursday’s speech to the National Association of Latino Elected and Appointed Officials (NALEO). After a grueling five-day bus trip through six states, Romney’s day off from the campaign trail served as an opportunity to bone up on a speech that could settle his campaign and rally his party.

“Romney hasn’t mentioned the ‘I’ word since the primary, and it’s something he needs to do, and needs to do sooner rather than later — it’s a big challenge on a big national issue that isn’t going away,” said Ana Navarro, a Republican strategist who focuses on Latino issues.

Romney’s speech takes place in Orlando, Fla., a critical swing state where Hispanic voters hold sway. Latinos are also a major voting bloc in the Southwest, a region that will play an important role in the election.

The gravity of the speech — and the desire for pitch-perfect messaging — was apparent early Wednesday during a conference call with reporters that campaign aides abruptly cut short after being asked repeatedly about Romney’s message on immigration.

“Gov. Romney is speaking at NALEO tomorrow, and he will have a few more things there to say about immigration,” said Romney policy director Lanhee Chen.

It’s a tall task for the Romney campaign, which has to keep Hispanics supportive of Obama’s policy from fully rejecting the GOP. But Romney, already wary of charges that he frequently changes positions and that he’s struggled to rally the Republican base, must also avoid completely abandoning the hard line on immigration he struck during the Republican primaries. 

“He’s got to walk a tightrope and not fall on the left or the right, because there’s no net to catch him,” said Navarro.

The one thing Romney won’t be able to do Thursday is completely ignore the immigration issue in favor of the economy, as he has at past campaign stops with Hispanic business leaders. 

Obama’s move has thrust the issue into the national headlines, and Republican leaders in Washington are looking to their party’s new standard-bearer for guidance. Senate Minority Leader Mitch McConnell (R-Ky.) said Tuesday most of his members were “going to withhold judgment” until hearing what Romney had to say.

The assembled Hispanic officials are also expecting Romney to give a substantive preview of what kind of reform he would propose as president.

“Well, we’re hopeful and expecting to hear that both Gov. Romney and the president will address the full spectrum of issues that Latino elected and appointed public officials are concerned about. Certainly the economy and jobs are at the top of the list, but our broken immigration system is something many of our members are frustrated over,” said Arturo Vargas, the executive director of NALEO, in an interview with MSNBC on Wednesday. 

Obama addresses the group Friday.

The audience is an important one to win over, argues Republican strategist Leslie Sanchez, who noted that the more than 1,000 governmental figures in attendance were essential to bring into the fold for grassroots outreach in November.

“It’s an opportunity for Romney to introduce himself and explain his positions and solutions and offer a kind of engraved invitation to be part of his campaign, and to be part of his alliance network,” Sanchez said. 

So far, Romney has provided only a vague sense of his position on immigration reform. Before the president’s move, the presumptive GOP nominee would only say he opposed the DREAM Act, although he later said he supported an exemption for illegal immigrations who served in the military. 

Otherwise, Romney deferred comment until after Sen. Marco Rubio (R-Fla.) developed a conservative version of the legislation. He lost that option on Tuesday, however, when Rubio said he was withholding any measure until after the election.

Since the president’s move, Romney has responded to most questions on the issue by accusing Obama of playing politics. And he’s not said whether he would repeal the order if Congress was unable to develop a reform plan legislatively, nor has he detailed specifically under what circumstances he believes the children of illegal immigrants should be allowed to stay in the United States.

But the longer Romney avoids the issue, the more likely it is to continue to distract from the economic messaging his campaign admits is central to winning the White House. Already, Romney’s poll numbers have slumped in the days following the president’s move.

According to a Bloomberg poll released Tuesday, 64 percent of likely voters backed the president’s shift on immigration policy, with more than two-thirds of independent voters supporting Obama. The poll also showed a bump in the national head-to-head presidential race, with some 53 percent of likely voters choosing Obama, versus just 40 percent for Romney.

“I have to begrudgingly admit that Obama’s immigration announcement Friday was a smart political move. I don’t like when it was done, how it was done, or why it was done, but like many other Hispanics I like what this means for those kids,” said Navarro.